Add some missing encodings in the ARM integrated assembler.

src/IceAssemblerARM32.cpp

 //===- subzero/src/IceAssemblerARM32.cpp - Assembler for ARM32 --*- C++ -*-===//
 //
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // Modified by the Subzero authors.
 //
 //===----------------------------------------------------------------------===//
 //
@@ skipping 181 matching lines @@
   // Rn.
   EncodedAsImmRegOffsetEnc3,
   // Value=0000000pu0w00nnnnttttiiiiiss0mmmm where nnnn is the base register Rn,
   // mmmm is the index register Rm, iiiii is the shift amount, ss is the shift
   // kind, p=1 if pre-indexed addressing, u=1 if offset positive, and w=1 if
   // writeback to Rn.
   EncodedAsShiftRotateImm5,
   // Value=000000000000000000000iiiii0000000 where iiii defines the Imm5 value
   // to shift.
   EncodedAsShiftImm5,
-  // i.e. iiiiiss0mmmm where mmmm is the register to rotate, ss is the shift
+  // Value=iiiiiss0mmmm where mmmm is the register to rotate, ss is the shift
   // kind, and iiiii is the shift amount.
   EncodedAsShiftedRegister,
+  // Value=ssss0tt1mmmm where mmmm=Rm, tt is an encoded ShiftKind, and ssss=Rms.
+  EncodedAsRegShiftReg,
   // Value is 32bit integer constant.
   EncodedAsConstI32
 };
 
 // Sets Encoding to a rotated Imm8 encoding of Value, if possible.
 IValueT encodeRotatedImm8(IValueT RotateAmt, IValueT Immed8) {
   assert(RotateAmt < (1 << kRotateBits));
   assert(Immed8 < (1 << kImmed8Bits));
   return (RotateAmt << kRotateShift) | (Immed8 << kImmed8Shift);
 }
@@ skipping 31 matching lines @@
       return CantEncode;
     Value = (Rotate << kRotateShift) | (Immed8 << kImmed8Shift);
     return EncodedAsRotatedImm8;
   }
   if (const auto *Const = llvm::dyn_cast<ConstantInteger32>(Opnd)) {
     Value = Const->getValue();
     return EncodedAsConstI32;
   }
   if (const auto *FlexReg = llvm::dyn_cast<OperandARM32FlexReg>(Opnd)) {
     Operand *Amt = FlexReg->getShiftAmt();
-    if (const auto *Imm5 = llvm::dyn_cast<OperandARM32ShAmtImm>(Amt)) {
-      IValueT Rm;
-      if (encodeOperand(FlexReg->getReg(), Rm) != EncodedAsRegister)
+    IValueT Rm;
+    if (encodeOperand(FlexReg->getReg(), Rm) != EncodedAsRegister)
+      return CantEncode;
+    if (const auto *Var = llvm::dyn_cast<Variable>(Amt)) {
+      IValueT Rs;
+      if (encodeOperand(Var, Rs) != EncodedAsRegister)
         return CantEncode;
-      Value =
-          encodeShiftRotateImm5(Rm, FlexReg->getShiftOp(), Imm5->getShAmtImm());
-      return EncodedAsShiftedRegister;
+      Value = encodeShiftRotateReg(Rm, FlexReg->getShiftOp(), Rs);
+      return EncodedAsRegShiftReg;
     }
-    // TODO(kschimpf): Handle case where Amt is a register?
+    // If reached, the amount is a shifted amount by some 5-bit immediate.
+    uint32_t Imm5;
+    if (const auto *ShAmt = llvm::dyn_cast<OperandARM32ShAmtImm>(Amt)) {
+      Imm5 = ShAmt->getShAmtImm();
+    } else if (const auto *IntConst = llvm::dyn_cast<ConstantInteger32>(Amt)) {
+      int32_t Val = IntConst->getValue();

[John, 2015/12/11 16:40:57]

is this code path still exercised? it shouldn't be. if it is, let me know and I
will fix the lowering.

[Karl, 2015/12/11 17:42:16]

Look at tests_lit/assembler/arm32/mov-reg.ll. If you comment out this "else if"
and then run "make -f Makefile.standalone check-lit", you will see the case.

+      if (Val < 0)
+        return CantEncode;
+      Imm5 = static_cast<uint32_t>(Val);
+    } else
+      return CantEncode;
+    Value = encodeShiftRotateImm5(Rm, FlexReg->getShiftOp(), Imm5);
+    return EncodedAsShiftedRegister;
   }
   if (const auto *ShImm = llvm::dyn_cast<OperandARM32ShAmtImm>(Opnd)) {
     const IValueT Immed5 = ShImm->getShAmtImm();
     assert(Immed5 < (1 << kShiftImmBits));
     Value = (Immed5 << kShiftImmShift);
     return EncodedAsShiftImm5;
   }
   return CantEncode;
 }
 
@@ skipping 309 matching lines @@
                                 EmitChecks RuleChecks, const char *InstName) {
   IValueT Rd = encodeRegister(OpRd, "Rd", InstName);
   IValueT Rn = encodeRegister(OpRn, "Rn", InstName);
   emitType01(Cond, Opcode, Rd, Rn, OpSrc1, SetFlags, RuleChecks, InstName);
 }
 
 void AssemblerARM32::emitType01(CondARM32::Cond Cond, IValueT Opcode,
                                 IValueT Rd, IValueT Rn, const Operand *OpSrc1,
                                 bool SetFlags, EmitChecks RuleChecks,
                                 const char *InstName) {
-
   IValueT Src1Value;
   // TODO(kschimpf) Other possible decodings of data operations.
   switch (encodeOperand(OpSrc1, Src1Value)) {
   default:
-    // TODO(kschimpf): Figure out what additional cases need to be handled.
-    return setNeedsTextFixup();
+    llvm::report_fatal_error(std::string(InstName) +
+                             ": Can't encode instruction");
+    return;
   case EncodedAsRegister: {
     // XXX (register)
     //   xxx{s}<c> <Rd>, <Rn>, <Rm>{, <shiff>}
     //
-    // cccc0000100snnnnddddiiiiitt0mmmm where cccc=Cond, dddd=Rd, nnnn=Rn,
-    // mmmm=Rm, iiiii=Shift, tt=ShiftKind, and s=SetFlags.
+    // cccc000xxxxsnnnnddddiiiiitt0mmmm where cccc=Cond, xxxx=Opcode, dddd=Rd,
+    // nnnn=Rn, mmmm=Rm, iiiii=Shift, tt=ShiftKind, and s=SetFlags.
     constexpr IValueT Imm5 = 0;
     Src1Value = encodeShiftRotateImm5(Src1Value, OperandARM32::kNoShift, Imm5);
     emitType01(Cond, kInstTypeDataRegister, Opcode, SetFlags, Rn, Rd, Src1Value,
                RuleChecks, InstName);
     return;
   }
   case EncodedAsShiftedRegister: {
     // Form is defined in case EncodedAsRegister. (i.e. XXX (register)).
     emitType01(Cond, kInstTypeDataRegister, Opcode, SetFlags, Rn, Rd, Src1Value,
                RuleChecks, InstName);
     return;
   }
   case EncodedAsConstI32: {
     // See if we can convert this to an XXX (immediate).
     IValueT RotateAmt;
     IValueT Imm8;
     if (!OperandARM32FlexImm::canHoldImm(Src1Value, &RotateAmt, &Imm8))
       llvm::report_fatal_error(std::string(InstName) +
                                ": Immediate rotated constant not valid");
     Src1Value = encodeRotatedImm8(RotateAmt, Imm8);
     // Intentionally fall to next case!
   }
   case EncodedAsRotatedImm8: {
     // XXX (Immediate)
     //   xxx{s}<c> <Rd>, <Rn>, #<RotatedImm8>
     //
-    // cccc0010100snnnnddddiiiiiiiiiiii where cccc=Cond, dddd=Rd, nnnn=Rn,
-    // s=SetFlags and iiiiiiiiiiii=Src1Value defining RotatedImm8.
+    // cccc001xxxxsnnnnddddiiiiiiiiiiii where cccc=Cond, xxxx=Opcode, dddd=Rd,
+    // nnnn=Rn, s=SetFlags and iiiiiiiiiiii=Src1Value defining RotatedImm8.
     emitType01(Cond, kInstTypeDataImmediate, Opcode, SetFlags, Rn, Rd,
                Src1Value, RuleChecks, InstName);
     return;
   }
+  case EncodedAsRegShiftReg: {
+    // XXX (register-shifted reg)
+    //   xxx{s}<c> <Rd>, <Rn>, <Rm>, <type> <Rs>
+    //
+    // cccc000xxxxfnnnnddddssss0tt1mmmm where cccc=Cond, xxxx=Opcode, dddd=Rd,
+    // nnnn=Rn, ssss=Rs, f=SetFlags, tt is encoding of type, and
+    // Src1Value=ssss01tt1mmmm.
+    emitType01(Cond, kInstTypeDataRegShift, Opcode, SetFlags, Rn, Rd, Src1Value,
+               RuleChecks, InstName);
+    return;
+  }
   }
 }
 
 void AssemblerARM32::emitType05(CondARM32::Cond Cond, IOffsetT Offset,
                                 bool Link, const char *InstName) {
   // cccc101liiiiiiiiiiiiiiiiiiiiiiii where cccc=Cond, l=Link, and
   // iiiiiiiiiiiiiiiiiiiiiiii=
   // EncodedBranchOffset(cccc101l000000000000000000000000, Offset);
   verifyCondDefined(Cond, InstName);
   AssemblerBuffer::EnsureCapacity ensured(&Buffer);
@@ skipping 1055 matching lines @@
 
 void AssemblerARM32::uxt(const Operand *OpRd, const Operand *OpSrc0,
                          CondARM32::Cond Cond) {
   constexpr const char *UxtName = "uxt";
   constexpr IValueT UxtOpcode = B26 | B25 | B23 | B22 | B21;
   emitSignExtend(Cond, UxtOpcode, OpRd, OpSrc0, UxtName);
 }
 
 } // end of namespace ARM32
 } // end of namespace Ice